It has long been a desirable goal to deliver some kind of benefit agent (e.g., silicone or other oils) to the skin through a personal wash composition.
In liquid cleansers, for example, cationic hydrophilic polymers such as Polymer JR.RTM. from Amerchol or Jaguar.RTM. from Rhone Poulenc have been used to enhance delivery of benefit agents (EP 93,602; WO 94/03152; and WO 94/03151). In applicants' copending application, U.S. Ser. No. 08/412,803 to Tsaur et al., separate hydrogel particles act as a structure to entrap the benefit agent in concentrated form.
In the subject invention, entrapment of benefit agent is achieved by producing compositions comprising emollient, wherein the medium in which the droplets are found (e.g., polyalkylene glycol) is thickened with a thickening agent (e.g., fumed silica) so that the droplets are entrapped in the polyethylene glycol. The emollient-containing, thickened carrier compositions may be dispersed throughout a bar (as in applicants copending application to Farrell et al. filed on same date as said application) or inserted as a concentrated composition into the bar (e.g., as a stripe).
Delivery of benefit agents (e.g., silicone) has proven difficult in bar compositions for a number of reasons. If the benefit agent does not remain sufficiently discrete from other components in the bar composition, for example, the generally hydrophobic benefit agent will contact hydrophobic materials in the bar mix rather than be free to deposit on the skin or other substrate. Thus, little or no benefit agent will be present in the final bar (after milling, plodding and extrusion of chips) to be delivered to the skin. If the benefit agent is too viscous, it tends to become entangled in the processing equipment and become too difficult to process.
U.S. Pat. No. 5,154,849 to Visscher et al. teaches bar compositions containing a silicone skin mildness/moisturizing aid component. In one embodiment, the silicone component may be mixed with a carrier which is selected to facilitate incorporation of the silicone. Preferred carrier is said to be polyethylene glycol. At column 16, the reference describes that silicone is mixed into melted Carbowax (polyethylene glycol). The mixture is cooled to form flakes and that the flakes are preferably added to an amalgamator.
The compositions of Visscher et al., however, do not teach or suggest thickening the alkylene glycol carrier with a thickening agent (e.g., fumed silica) in order to more readily entrap the emollient. Because the silicone drops are not "contained" by the carrier (e.g., alkylene glycol carrier) in which they are delivered, the benefit agent silicone readily escapes from the carrier and significantly interferes with bar processing (e.g., a viscous, gooey mess is formed which cannot be readily processed) and readily clogs the machinery. By contrast, the entrapped emollient droplets of the invention do not interfere with processing.
Moreover, the present invention is particularly concerned with inserting (e.g., by injection, extrusion or coextrusion) separate compositions comprising the entrapped emollient droplets (i.e., entrapped in the thickened carrier) into bars such that they occupy concentrated regions or domains of the bar (rather than being dispersed as in copending application to Farrell et al., filed on same day). Visscher et al. neither teaches nor suggests concentrated, macroscopic regions of emollient drops from which deposition is enhanced.
Finally in a copending application to He et al., applicants teach low viscosity oils or emollients which are pre-thickened with hydrophobic polymers having low degree of crystallinity. That application teaches thickening of the oils themselves (i.e., thickening low viscosity oils) rather than thickening carriers in which emollients (preferably large size droplet emollients) are found.